title: Mucosal immunogenicity of a holotoxin-like molecule containing the serine-rich Entamoeba histolytica protein (SREHP) fused to the A2 domain of cholera toxin.
abstract: One strategy for the induction of mucosal immune responses by oral immunization is to administer the antigen in conjunction with cholera toxin. Cholera toxin consists of one A polypeptide (CTA) which is noncovalently linked to five B subunits (CTB) via the A2 portion of the A subunit (CTA2). Coupling of antigens to the nontoxic B subunit of cholera toxin may improve the immunogenicity of antigens by targeting them to GM1 ganglioside on M cells and intestinal epithelial cells. Here, we describe the construction of a translational fusion protein containing the serine-rich Entamoeba histolytica protein (SREHP), a protective amebic antigen, fused to a maltose binding protein (MBP) and to CTA2. When coexpressed in Escherichia coli with the CTB gene, these proteins assembled into a holotoxin-like chimera containing MBP-SREHP-CTA2 and CTB. This holotoxin-like chimera (SREHP-H) inhibited the binding of cholera toxin to GM1 ganglioside. Oral vaccination of mice with SREHP-H induced mucosal immunoglobulin A (IgA) and serum IgG antiamebic antibodies and low levels of mucosal anti-CTB antibodies. Our studies confirm that the genetic coupling of antigens to CTA2 and their coexpression in E. coli can produce holotoxin-like molecules that are mucosally immunogenic without the requirement for supplemental cholera toxin, and they establish the SREHP-H protein as a candidate for evaluation as a vaccine to prevent amebiasis.
authors.affiliation: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: F
authors.initials: F
authors.lastname: Sultan
authors.forename: L L
authors.initials: LL
authors.lastname: Jin
authors.forename: M G
authors.initials: MG
authors.lastname: Jobling
authors.forename: R K
authors.initials: RK
authors.lastname: Holmes
authors.forename: S L
authors.initials: SL
authors.lastname: Stanley
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D002772:Cholera Toxin / Q000276:immunology*; D004748:Entamoeba histolytica / Q000276:immunology*; D005260:Female; D018928:Immunity, Mucosal; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D051379:Mice; D008807:Mice, Inbred BALB C; D015800:Protozoan Proteins / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D002772:Cholera Toxin